342 



CARNEGIE INSTITUTION OF WASHINGTON. 



ABSTRACTS OF PUBLICATIONS AND INVESTIGATIONS. 



Preliminary results of ocean magnetic observations on the Carnegie from Colombo, Ceylon, 

 to Fremantle, Western Australia, and Lyttelton, New Zealand, July to Octo- 

 ber 1920. J. P. Ault. Terr. Mag., vol. 25, 145-162 (December 1920). 



Preliminary results of ocean magnetic observations on the Carnegie from Lyttelton to Tahiti, 

 Fanning Island, San Francisco, and Honolulu, November 1920 to April 1921. 

 J. P. Ault. Terr. Mag., vol. 26, 15-24 (March-June 1921). 



Preliminary results of ocean magnetic observations on the Carnegie from Honolulu to Pago 

 Pago, April to June, 1921. J. P. Ault. Terr. Mag., vol. 26, 91-95 (Septem- 

 ber 1921). 



These three papers give the preliminary results of the magnetic observa- 

 tions on the Carnegie during the present cruise (No. VI) during July 1920 to 

 June 1921. Notes on the various passages are given; in addition to the general 

 details of the passages, they include pertinent remarks regarding auxiliary 

 observations, determinations of currents, and corrections determined for 

 geographical positions of islands in the Pacific which were visited. 



Table 1 will serve to show for the period, October 1920 to October 1921, 

 the magnitudes of the chart differences as determined from a comparison of the 

 Carnegie observed values of the magnetic elements with values scaled from the 

 most recent magnetic charts: For declination, U. S. Hydrographic Office 

 No. 2406 for 1920 and British Admiralty Nos. 3776 and 3777 for 1917; for 

 inclination, U. S. Hydrographic Office No. 1700 for 1920; and for horizontal 

 intensity, U. S. Hydrographic Office No. 1701 for 1920. The new material 

 for these charts was supplied almost entirely by the Department of Terrestrial 

 Magnetism. Secular variation corrections were applied to the magnetic 

 declinations scaled from the charts. 



In order to explain the significance of the letters E, W, N, S as affecting the 

 apphcation of the chart differences, it may be stated that E and N have been 

 treated as being plus, W and S as minus, the chart difference being equal to 

 the Carnegie value minus the chart value. The horizontal intensity is always 

 regarded as positive, and the signs, plus and minus, have their usual signifi- 

 cance. 



i 



'Units of third decimal C. G. S. 



Preliminary average annual changes of the magnetic elements in the Indian and Pacific 

 Oceans, 1905 to 1920. J. P. Ault. 



The average annual changes in the values of the magnetic elements given in 

 tables 2 and 3 were obtained by using the results of observations made on the 

 Carnegie and the Galilee in the vicinity of the intersections of their various 

 tracks. The magnitude of the change in declination over the southern part 

 of the Indian Ocean is especially worthy of attention. The method employed 



